Automotive hinges are generally configured to include a door component that is rigidly attached to a closure panel and a body component that is rigidly attached to a body structure. This structural attachment of the components can be achieved by welding, riveting, bolting or similar mechanical fastening means. The simple rotary motion of the door component relative to the body component is normally achieved by a pivot pin and associated bearing surfaces. The pivot pin is configured to be rigidly attached to one of the hinge components while the other component freely rotates around the pivot pin via one or more bearing surfaces. It is normal practice to utilize two of these hinge assemblies, vertically offset with coaxially aligned pivot pins, to attach a closure panel to a body structure.
The body and door components of an automotive hinge are commonly constructed from either steel or aluminum using stamping, forging, casting, roll forming or extruding. Each component is generally configured with one or more mounting surfaces and a pair of pivot arms that contain pivot axis holes. The pivot arms are structurally connected by some form of bridge or by the mounting surface. It is common practice to create the required pivot bearing surface by assembling bushings into the pivot axis holes of the door component. A pivot pin is inserted through the pivot bushings of the door component and structurally attached to the body component through the pivot axis holes using knurling, interference fits, riveting, staking or similar means of material upsetting.
The body component is structurally attached to a vehicle body structure via its mounting surface using bolting, welding, bonding, riveting or similar fastening means. The door component is similarly structurally attached to a vehicle closure panel via its mounting surface using bolting, welding, bonding, riveting or similar fastening means.
Bolted automotive hinge systems typically utilize a minimum of two fasteners per hinge component. Complex formations are therefore required to provide the necessary pivot axis hole locations, mounting surfaces, structural integrity, fastener locations and clearance offsets in a single piece component. Forgings and casting are well suited to providing these necessarily complex shapes but carry a significant cost penalty in comparison to press formed metal stampings. Metal stamping is generally considered the most cost effective method of creating hinge components but formation shape is somewhat limited. Additionally, complex configurations generally result in large quantities of unused scrap material being produced during the press forming process.
FIG. 1 illustrates a common prior art embodiment of an automotive door hinge assembly (1) configured from a press formed body component (2), a press formed door component (3), a pivot pin (4) and two pivot bushings (25)(26). The body component (2) is configured with a pair of pivot arms (6)(7) and a large mounting surface (8) that is adapted to be structurally attached to a vehicle body structure via mounting holes (9)(10) and two corresponding threaded fasteners. These mounting holes (9)(10) are spaced at an adequate distance to assure sufficient load spreading into the vehicle body structure. The pivot arms (6)(7) are configured with a pair of pivot holes (11)(12) adapted to accept and rigidly capture the pivot pin (4) via knurling, interference fits, riveting, staking or similar means of material upsetting. The distance from the mounting holes (9)(10) to the pivot holes (11)(12) is dictated by the vehicle's closure panel and body configuration and can be substantial. The door component (3) is configured with a pair of pivot arms (13)(14), a structural bridge (21) and a pair of mounting surfaces (15)(16) that are adapted to be structurally attached to a vehicle closure panel via mounting holes (17)(18) and two corresponding threaded fasteners. These mounting holes (17)(18) are spaced at an adequate distance to assure sufficient load spreading into the vehicle closure panel. The pivot arms (13)(14) are configured with a pair of pivot holes (19)(20) adapted to accept the pivot bushings (25)(26) that facilitate rotation around the pivot pin (4). The distance from the mounting holes (17)(18) to the pivot holes (19)(20) is dictated by the vehicle's closure panel and body configuration and can be substantial. Both the body component (2) and door component (3) are press formed from a flat sheet of steel and, due to their complex shapes a significant amount of scrap material is created during the stamping process. FIG. 2 illustrates the flat blank layout of both the prior art body component (2a) and the door component (3a) as well as the scrap material (22) shown cross hatched associated with the stamping process. Despite the considerable scrap material (22) generated in this configuration, the press formed manufacturing technique is still more cost effective than either casting or forging.